This is on initialisation of the crop popup:
Notice: Undefined index: parent_post_id in (...)\wp-content\plugins\crop-thumbnails\functions\editor.php on line 148

Also... I'm only seeing the 'thumbnail' on the right. Shouldn't it also show the medium and large version of the image there?

After defining a crop and saving the 'Please wait...' doesn't go away (the thumb does get cropped though). The ajax json callback has a PHP error:
Notice: Undefined variable: dest_path in (...)\wp-content\plugins\crop-thumbnails\functions\save.php on line 219
{"debug":"saveThumbnail()\n-------------------thumb:(...)\/wp-content\/uploads\/2013\/01\/463226253TUKCrS_fs-2-150x150.jpg\nthumb tmp:(...)\/wp-content\/uploads\/tmp\/463226253TUKCrS_fs-2-150x150.jpg\n","success":1358246440}